by MAURICE K. SEGUIN
Department of Geology, University of Laval, Quebec, Canada
An analysis of the intensity and direction of remanent magnetism is used
to determine the origin and the age of two itabirite deposits from the southern
extension of the Labrator through. This study indicates the remanent magnetism
is the dominant form of magnetism present in the samples gathered from these
orebodies. The knowledge of NRM characteristics is useful in the interpretation
of ground and AM surveys to locate new deposits and for the development of
known orebodies.
The original direction of magnetization acquired by both magnetite and hematite
deposits at the time of deposition is erased and replaced by a chemical and/or
thermal magnetization during dynamic and thermal metamorphism of these orebodies.
The paleomagnetic age obtained sees through the 1000 m.y. K/Ar isothron transparency
of the Grenville orogeny.